Search Results (113)

Laizhou Bay, a semi-enclosed bay, is prone to storm surges from cold waves due to its geographic and environmental characteristics. This study uses satellite data, in situ measurements, and the MIKE numerical model to analyze storm surges along Laizhou Bay’s coast under no-dike conditions. It examines the surges caused by cold waves with different intensities and directions. This study provides the storm surge disaster risk levels along Laizhou Bay’s coast. The results show that the maximum sustained wind speed during cold waves is distributed between the NW and NE. The NE wind direction causes the most severe storm surge along Laizhou Bay. Under NE-directed cold waves with level 12 wind, the maximum risk areas for Level III and IV are approximately 1341 km² and 1294 km², respectively. Dongying, Shouguang, and Hanting exhibit large Level I and II risk zones. The maximum seawater intrusion distance along the Kenli coast is about 41 km. The coastal segment from Kenli to Changyi is most severely affected by storm surges. It is recommended to effectively maintain and heighten seawalls along this segment to mitigate storm surge disasters caused by strong NE winds. Full article

This study systematically investigates the effects of shell ash (SA) content (0–10%) on early moisture evolution, pore structure, and hydration kinetics in cement paste using LF-NMR and NG-I-D hydration kinetic models. Key findings include the following: (1) Increased SA content significantly alters moisture phase distribution. Low contents (≤8%) consume free water through rapid CaO hydration, promoting C-S-H gel densification. However, 10% SA causes reduced moisture in 0.16–0.4 μm gel micropores (due to hindered ion diffusion) and abrupt increases in 0.63–2.5 μm pores. (2) Porosity first decreases then increases with SA content, reaching minimum values at 3–5% and 8%, respectively. The 10% content induces abnormal porosity growth from localized over-densification following polynomial fitting (R² = 0.966). (3) Krstulovic–Dabic model analysis reveals three consecutive hydration stages: nucleation–growth (NG), phase boundary reaction (I), and diffusion control (D). The NG stage shows the most intense reactions, while the D stage dominates (>60% contribution), with high model fitting accuracy (R² > 0.9). (4) SA delays nucleation/crystal growth, inducing needle-like crystals at 3% content. Mechanical properties exhibit quadratic relationships with SA content, achieving peak compressive strength (18.6% increase vs. control) at 5% SA. This research elucidates SA content thresholds governing hydration kinetics and microstructure evolution, providing theoretical support for low-carbon cementitious material design. Full article

Clams from the Fujian group, the Laizhou group, and the zebra strain group were used in this investigation; their shell lengths were 1.0 cm, 1.5 cm, and 2.0 cm, respectively. Tests were conducted on substrates with particle sizes ranging from 151 to 180 µm, 181 to 250 µm, 251 to 425 µm, and 426 to 850 µm. Both centralized and decentralized sowing modes were used. According to the findings, the clams with the 1.0 cm shell length had the highest burrowing rate and the lowest ET₅₀. From 0 to 120 min, the burrowing rate of the zebra strain group was higher than that of the other groups. Clams with shell lengths of 1.0 cm and 1.5 cm had similar burrowing rates at the end of the test, with the zebra strain group having the highest burrowing rate. Manila clams burrowed more quickly when the substrate’s particle sizes were between 181 and 425 µm. The clam burrowing rates in the decentralized sowing mode were high during the first 20 min of the test, but at the end of the test, there was no significant difference between the two sowing modes (p > 0.05). In summary, there were differences in the burrowing ability among the three groups. The clams with a shell length of 1.0 cm in the three groups had a higher burrowing efficiency, and the decentralized sowing mode was more conducive to the clams quickly burrowing into the substrate. Full article

As China’s largest peninsula, the Shandong Peninsula faces recurrent threats from both tropical and extratropical cyclone-induced storm surges. Understanding the distinct mechanisms governing these surge types is critical for developing targeted coastal hazard mitigation strategies. This investigation employs the FVCOM-SWAVE coupled wave–current model to conduct numerical simulations and comparative analyses of two 2022 surge events, Typhoon Muifa (tropical) and the “221003” extratropical surge. The results demonstrate that hydrodynamic responses exhibit strong dependence on surge-generating meteorological regimes. Tropical surge dynamics correlate closely with typhoon track geometry, intensity gradients, and asymmetric wind field structures, manifesting rightward-biased energy intensification relative to storm motion. Conversely, extratropical surge variations align with evolving wind-pressure configurations during cold air advection, driven by synoptic-scale atmospheric reorganization. The hydrodynamic environmental response in the sea areas surrounding Jiaodong and Laizhou Bay is particularly pronounced, influenced by the intensity of wind stress on the sea surface, as well as the bathymetry and coastal geometry. Full article

Benthic microbial communities are a vital component of coastal subtidal zones, playing an essential role in nutrient cycling and energy flow, and are fundamental to maintaining the stability and functioning of marine ecosystems. However, the response of benthic prokaryotic and eukaryotic microbial communities to environmental changes remains poorly understood. Herein, we conducted a nearly semimonthly annual sampling survey to investigate the temporal patterns and underlying mechanisms of benthic prokaryotic and eukaryotic microbial communities in the subtidal sediments of Sanshan Island, situated in the eastern Laizhou Bay of the Bohai Sea, China. The results showed that the temporal variations in benthic microbial communities followed a distinct seasonal pattern, with turnover playing a more dominant role in community succession. Nonetheless, contrasting temporal variations were observed in the alpha diversity of benthic prokaryotic and eukaryotic microbial communities, as well as in the dominant taxa across different microbial communities. Water temperature, dissolved oxygen, electrical conductivity, salinity, total nitrogen (TN), NH₄⁺, and PO₄³⁻ were identified as the predominant environmental drivers. The assembly of benthic microbial communities was driven by different ecological processes, in which stochastic processes mainly shaped the benthic prokaryotic communities, while deterministic processes dominated the assembly of benthic eukaryotic microbial communities. Interactions within benthic microbial communities were primarily characterized by mutualistic or cooperative relationships, but the ability of prokaryotic and eukaryotic microbial communities to maintain stability under environmental disturbances showed notable differences. These results shed light on the temporal dynamics and potential driving mechanisms of benthic prokaryotic and eukaryotic microbial communities under environmental disturbances, highlighting the distinct roles of prokaryotic and eukaryotic communities in coastal subtidal zones and providing valuable insights for the management and conservation of coastal subtidal marine ecosystems. Full article

Analyzing the mechanisms of accidents is essential for clarifying the accident evolution process, devising preventive measures, and achieving proactive accident management. To address the potential issues in existing accident causation theories, such as the unclear distinction between direct causes and incomplete accident evolution pathways in enterprise-level accident prevention analysis, this study systematically reviewed the elements involved in safety management activities and their interrelationships. We identified the central role of human factors in the accident evolution process and developed a full lifecycle evolution model for industrial accidents, which begins with hazard identification and follows a safety management logic as its primary framework. This model provides a clear pathway for constructing enterprise-level risk control lists and accident prevention schemes. The model’s effectiveness was validated through its application to China’s underground metal mining industry. Drawing on Chinese laws and regulations as well as accident investigation reports, this study identifies 11 common types of accidents in underground metal mines and maps their evolution pathways from a complex systems perspective. Quantitative data from 61 accident reports were used to pinpoint the core factors and critical pathways leading to these various accidents. The study also analyzes prevention strategies and proposes new countermeasures to control the propagation of accident risks. Practical applications of the model demonstrate that emphasizing human factors enhances the effectiveness and accuracy of enterprise-level accident analysis and risk management. Full article

Saltwater intrusion is one of the most significant groundwater challenges in the southern Laizhou Bay. Previous studies have predominantly focused on regional scales, leaving the vertical saltwater intrusion pattern relatively underexplored. This knowledge gap hinders the effective prevention and control of saltwater intrusion. This study utilized hydrochemical and stable isotopic methods combined with hydrochemical facies evolution diagrams to investigate the groundwater evolution and the processes of saltwater intrusion in a typical profile and saline–fresh groundwater transition zones. The results showed that the groundwater types in the study area were complex and diverse, with fresh groundwater, saline groundwater, and brine. Stable isotope and hydrochemical analyses indicated that mixing and evaporation of seawater were the predominant processes governing the evolution and salinity of groundwater. In the south of the typical profile, carbonate dissolution played a significant role, and the silicate dissolution may represent the primary water–rock interaction in the saline–fresh groundwater transition zones. Groundwater samples from various locations within the study area exhibited different stages of hydrochemical facies evolution, and the majority of the typical profile samples were in the salinization phase during the mixing process. The saltwater intrusion in the saline–fresh groundwater transition zone primarily occurred between −20 and −30 m, exhibiting a wedge-shaped saltwater intrusion pattern. This study enhanced the understanding of vertical saltwater intrusion. Full article

Drawing upon an understanding of the distribution characteristics of groundwater in the Taoshan rock mass within the Yushan Uplift region of southern Jiangxi, this study utilizes mathematical statistics, ion ratio coefficients, factor analysis, and mineral dissolution equilibrium methods to characterize in detail the hydrochemical features of groundwater in humid mountainous areas. Furthermore, the study delves into the lithological source control and the primary natural mechanisms that underlie these characteristics. The results indicate that the average pH of groundwater in the study area is 7.13, classifying it as weakly alkaline. The dominant cations are Ca²⁺ and Na⁺, accounting for 61% and 26% of the total cations, respectively, while the dominant anion is HCO₃⁻, constituting 91% of the total anions. The total dissolved solids (TDS) range from 37.93 mg/L to 228.16 mg/L, indicating low mineralization. The groundwater types are primarily HCO₃-Ca·Na and secondarily HCO₃-Ca. The groundwater type is mainly controlled by rock weathering, with the primary ion sources influenced by the weathering and dissolution of silicate rocks, supplemented by contributions from carbonate rock dissolution. Ion ratio analysis further confirms that the major ions in groundwater predominantly originate from the weathering of silicate minerals, with minimal influence from human activities. Na⁺, K⁺, and H₂SiO₃ are primarily derived from the weathering and dissolution of silicate rocks, while the weathering and dissolution of carbonate rocks (e.g., calcite) significantly contribute to Ca²⁺ and Mg²⁺. TDS shows significant positive correlations with Mg²⁺, SO₄²⁻, HCO₃⁻, Na⁺, and Ca²⁺, with the most pronounced correlations observed between TDS and Ca²⁺ and HCO₃⁻, exhibiting a correlation coefficient of 0.89. Factor analysis reveals that the first principal component has relatively high loadings for TDS, Ca²⁺, HCO₃⁻, Mg²⁺, and SO₄²⁻. Additionally, among 45 natural spring water samples, 36 exhibit metasilicic acid (H₂SiO₃) concentrations exceeding 30 mg/L, meeting the standards for metasilicic acid mineral water and demonstrating significant potential for development and utilization. Full article

Water residence time (WRT) is a crucial parameter for evaluating the rate of water exchange and it serves as a timescale for elucidating hydrodynamic processes, pollutant dispersion, and biogeochemical cycling in coastal waters. This study investigates the tidal-driven WRT patterns in the Bohai and Yellow Seas (collectively known as BYS) by employing a tidal model in conjunction with an adjoint WRT diagnostic model and explores the influence of tidal constituents on WRT. The findings indicate that the tidal-driven WRT in the BYS is approximately 2.11 years, exhibiting a significant spatially heterogeneous distribution. The WRT pattern shows a strong correlation with the pattern of tidal-driven Lagrangian residual currents (LRCs). Semidiurnal tides have a more pronounced effect on WRT than diurnal tides. Semidiurnal tides significantly reduce WRT across the entire BYS, while diurnal tides predominantly influence WRT in the Bohai Sea (BS). The M₂ tidal constituent is the most influential in decreasing WRT and enhancing water exchange, owing to its dominant energy contribution within the tidal system. In contrast, the S₂ tidal constituent has a minimal effect; however, its interaction with the M₂ tidal constituent plays a significant role in reducing the WRT. The K₁ and O₁ constituents exert more localized effects on WRT, particularly in the central BS, where their energy ratios relative to M₂ are relatively high. Although the amplitude of the S₂ constituent exceeds that of K₁ and O₁, its contribution to LRC—and consequently to WRT—is limited due to the overlapping tidal wave with M₂. This research contributes to a deeper understanding of the influence of tidal dynamics on long-term water transport and associated timescales, which are vital for enhancing predictions of material transport and ecosystem dynamics in tidal-dominated environments. Full article

The northward expansion of Spartina alterniflora (S. alterniflora) poses a profound ecological threat to coastal ecosystems and biodiversity along China’s coastline. This invasive species exhibits strong adaptability to colder climates, facilitating its potential spread into northern regions and underscoring the urgent need for a nuanced understanding of its spatial distribution and invasion risks to inform evidence-based ecosystem management strategies. This study employed multi-temporal Sentinel-1/2 imagery (2016–2022) to map and predict the spread of S. alterniflora in Bohai Bay. An object-based random forest classification achieved an overall accuracy above 92% (κ = 0.978). Over the six-year period, the S. alterniflora distribution decreased from 46.60 km² in 2016 to 12.56 km² in 2022, reflecting an annual reduction of approximately 5.67 km². This decline primarily resulted from targeted eradication efforts, including physical removal, chemical treatments, and biological competition strategies. Despite this local reduction, MaxEnt modeling suggests that climate trends and habitat suitability continue to support potential northward expansion, particularly in high-risk areas such as the Binhai New District, the Shandong Yellow River Delta, and the Laizhou Bay tributary estuary. Key environmental drivers of S. alterniflora distribution include the maximum temperature of the warmest month, mean temperature of the wettest quarter, isothermality, sea surface temperature, mean temperature of the warmest quarter, and soil type. High-risk invasion zones, covering about 95.65 km². These findings illuminate the spatial dynamics of S. alterniflora and offer scientific guidance for evidence-based restoration and management strategies, ensuring the protection of coastal ecosystems and fostering sustainable development. Full article

Episodic sedimentary processes with significant changes in sedimentation rate have occurred on the East Hainan Coast, the inner shelf of the South China Sea, since the Last Glacial Maximum. In particular, the early-Holocene (~11.5–8.7 ka) rapid sedimentation at a mean rate of ~4.90 m/ka is crucial to understand the processes of terrigenous input to the ocean, carbon cycling and climate control in coastal-neritic sedimentary evolution. However, the chronological framework and the detailed environmental evolution remain uncertain. In this study, core sediments collected from the East Hainan Coast (code: NH01) were used to revisit the characteristics of luminescence signals by comparing the dating results using the blue-light stimulated luminescence (blue-OSL) ages and previously published post-infrared blue-light stimulated luminescence (pIR-blue OSL) ages. The results showed that both the ages agreed with each other for the fine-grained quartz fraction. The refined chronology of the early-Holocene deposits on the East Hainan Coast with higher resolution suggested that the sedimentation rate was ~0.60 m/ka before 10.97 ka, while it increased abruptly to ~5.89 m/ka during the period of 10.97–9.27 ka. According to the refined OSL chronology and the high-resolution (~2.5 cm) titanium intensity using X-ray fluorescence (XRF) scanning, the rapid sedimentation during the early Holocene was likely controlled by increased terrigenous input. The variation in Ti flux reflected the differential response between two meltwater pulse (MWP) events under the combined effects of enhanced early-Holocene monsoons and localized freshwater input. These findings highlight the compound controls of global ice-volume change, monsoon dynamics and coastal geomorphic evolution on sedimentary processes. Full article

Cemented tailings backfill (CTB) plays an important role in mine filling operations. In order to study the long-term stability of CTB under the dynamic disturbance of deep wells, ultrafine cemented tailings backfill was taken as the research object, and the true triaxial hydraulic fracturing antireflection-wetting dynamic experimental system of coal and rock was used to carry out a static true triaxial compression test, a true triaxial compression test under unidirectional disturbance, and a true triaxial compression test under bidirectional disturbance. At the same time, the acoustic emission monitoring and positioning tests of the CTB were carried out during the compression test. The evolution law of the mechanical parameters and deformation and failure characteristics of CTB under different confining pressures is analyzed, and the damage constitutive model of the filling body is established using stochastic statistical theory. The results show that the compressive strength of CTB increases with an increase in intermediate principal stress. According to the change process of the acoustic emission ringing count over time, the triaxial compression test can be divided into four stages: the initial active stage, initial calm stage, pre-peak active stage, and post-peak calm stage. When the intermediate principal stress is small, the specimen is dominated by shear failure. With an increase in the intermediate principal stress, the specimen changes from brittle failure to plastic failure. The deformation and failure strength of CTB are closely related to its loading and unloading methods. Under a certain stress intensity, compared with unidirectional unloading, bidirectional unloading produces a greater deformation of the rock mass, and the failure strength of the rock mass is higher. This study only considers the confining pressure within the compressive limit of the specimen. Future research can be directed at a wider range of stresses to improve the applicability and reliability of the research results. Full article

The advancement of pre-trained language models (PLMs) has provided new avenues for addressing text classification challenges. This study investigates the applicability of PLMs in the categorization and automatic classification of short-text safety hazard information specifically within mining industry contexts. Leveraging the superior word embedding capabilities of encoder-based PLMs, the standardized hazard description data collected from mine safety supervision systems were vectorized while preserving semantic information. Utilizing the BERTopic model, the study successfully mined hazard category information, which was subsequently manually consolidated and labeled to form a standardized dataset for training classification models. A text classification framework based on both encoder and decoder models was designed, and the classification outcomes were compared with those from ensemble learning models constructed using Naive Bayes, XGBoost, TextCNN, etc. The results demonstrate that decoder-based PLMs exhibit superior classification accuracy and generalization capabilities for semantically complex safety hazard descriptions, compared to Non-PLMs and encoder-based PLMs. Additionally, the study concludes that selecting a classification model requires a comprehensive consideration of factors such as classification accuracy and training costs to achieve a balance between performance, efficiency, and cost. This research offers novel insights and methodologies for short-text classification tasks, particularly in the application of PLMs in mine safety management and hazard analysis, laying a foundation for subsequent related studies and further improvements in mine safety management practices. Full article

The secure and effective use of marginal water resources, such as brackish water, plays a crucial role in ensuring food security and promoting the sustainable development of agricultural land. This paper conducted indoor soil column experiments to simulate the infiltration of brackish water (0, 1, 3, and 5 g L⁻¹) in order to study the effects of infiltration on the movement of soil water and salt, aiming to address the critical challenge of utilizing marginal water resources in coastal saline-alkali areas. The result showed that, as salt content increases, the movement speed of the moisture front and soil infiltration rate gradually decrease over the same period of time. The moisture front progress and infiltration volume showed a positive correlation. The moisture content of the soil profile gradually decreased, within the soil depth range of 0–40 cm, except for the 5 g L⁻¹ saline water infiltration, and the Cl⁻ content increased, while the other treatments showed a trend of first decreasing and then increasing. The higher salt content at the same depth, the higher the Na⁺ and Cl⁻ contents. Under different irrigation water volume conditions, the soil profile conductivity shows a trend of first decreasing and then increasing. The research findings advance fundamental understanding of salinity-driven soil hydrological processes, offering theoretical support for the sustainable utilization of brackish water, balancing agricultural water demand and soil health in coastal areas. Full article

Land use/land cover (LULC) change has greatly altered ecosystem carbon storage capacity and may eventually profoundly impact global climate change. Characterizing the LULC change and its impact on wetland ecosystem carbon stock provides useful data and insights that can guide decision-making procedures aimed at achieving sustainable development objectives. The Yellow River Delta (YRD) represents the most intact coastal wetland and is considered to be the most recent wetland ecosystem in China. It exhibits significant carbon stock capacity and ecological value. Based on the LULC data of the YRD in 2002, 2007, 2012, 2017, and 2022, this paper quantitatively evaluates the spatiotemporal changes in LULC and carbon stock in the region and analyzes the response characteristics of carbon stock to LULC change. The results show significant reductions in cropland and tidal flat wetland areas from 2002 to 2022, resulting in a decrease of 1,428,735.77 t and an increase of 139,856.58 t in carbon stock, respectively. The built-up land area expanded considerably, and carbon stock was lost by 1,467,915.82 t. Spatially, the carbon stock exhibited a pattern of “low along the coast, high inland; low in the center, high around the periphery”. In addition, protecting cropland, reducing building, facilitating the conversion of reservoirs and ponds to forest, and transforming tidal flat wetlands into reservoirs and ponds can increase the region’s carbon storage capacity. These findings provide valuable insights for regional carbon management strategies and ecological protection policies, supporting the sustainable development goals of the Yellow River Delta. Full article